The segments of track of a tracklaying vehicle are pivoted together at pivots each formed by a pin having ends force-fitted into one of the segments and passing through a guide or sleeve secured to the other segment, normally also by force-fitting. It is necessary to lubricate and protect the contacting surfaces of each of these pivots, so a seal is normally provided between the member constituted by the one segment and the relatively rotatable or pivotable member constituted by the adjacent track segment at each pivot.
To this end as described in U.S. Pat. No. 4,030,730 an outwardly open groove is formed at each of these pivots and a U-section seal is fitted therein. In order to insure good contact between each side of the seal and the respective flank of the groove it is known to provide a solid-section nonmetallic and elastomeric load ring between the sides of the seal.
Such an arrangement works satisfactorily at normal operating temperatures. When the temperature rises above or falls below a relatively limited range, however, the effectiveness of the elastomeric load ring drops considerably. In the high temperature range the load ring becomes very soft and is almost completely ineffective to press the sides of the seal against the flanks of the groove, and in the low temperature range the elasticity of the load ring declines considerably so that its effectiveness is also reduced. What is more, the provision of such a massive load ring inside the seal limits the amount of fluid lubricant, normally grease, which the joint can be packed with. Thus it is difficult to provide a large quantity of grease at this very critical region which is exposed to very severe treatment as it forms the most roughly used portion of the tracklaying vehicle.